And, sticking to conceptual art, I'll happily defend John Cage's 4'33": a few sentences on a piece of paper that read like a stunt, but when actually experienced gave me a new understanding of the process of listening. If that's not "a skillful archer send[ing] an arrow into an exceedingly narrow target," I don't know what is.

The same is true of LaMonte Young's X For Henry Flynt. But you have to hear it. Reading about it won't do much for you.

The ongoing popularity of Magritte's "Ceci n'est pas une pipe" and Escher's "Ascending and Descending" as logic/science illustrations would seem to indicate that rationalists are comfortable enough with conceptual art when it suits them.